diff --git a/configure.ac b/configure.ac
index a3d38e86dfcc7bfaf94fc2a24d77b4441edc47f2..cbdbf5469bee0b3dec966e8c15955929d2445bec 100644
--- a/configure.ac
+++ b/configure.ac
@@ -112,6 +112,9 @@ if test "$enable_mpi" = "yes"; then
 fi
 AM_CONDITIONAL([HAVEMPI],[test $enable_mpi = "yes"])
 
+# Indicate that MPIRUN can be modified by an environement variable
+AC_ARG_VAR(MPIRUN, Path to the mpirun command if non-standard)
+
 # Need C99 and inline support.
 AC_PROG_CC_C99
 AC_C_INLINE